// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_WASM_SIGNATURE_MAP_H_
#define V8_WASM_SIGNATURE_MAP_H_

#include <unordered_map>

#include "src/signature.h"
#include "src/wasm/value-type.h"

namespace v8 {
namespace internal {

    namespace wasm {

        // A signature map canonicalizes signatures into a range of indices so that
        // two different {FunctionSig} instances with the same contents map to the
        // same index.
        class V8_EXPORT_PRIVATE SignatureMap {
        public:
            // Allow default construction and move construction (because we have vectors
            // of objects containing SignatureMaps), but disallow copy or assign. It's
            // too easy to get security bugs by accidentally updating a copy of the map.
            MOVE_ONLY_WITH_DEFAULT_CONSTRUCTORS(SignatureMap);

            // Gets the index for a signature, assigning a new index if necessary.
            uint32_t FindOrInsert(const FunctionSig& sig);

            // Gets the index for a signature, returning {-1} if not found.
            int32_t Find(const FunctionSig& sig) const;

            // Disallows further insertions to this signature map.
            void Freeze() { frozen_ = true; }

        private:
            bool frozen_ = false;
            std::unordered_map<FunctionSig, uint32_t, base::hash<FunctionSig>> map_;
        };

    } // namespace wasm
} // namespace internal
} // namespace v8

#endif // V8_WASM_SIGNATURE_MAP_H_
